Biomedical subjects

Q Zhang

Publications and source records attributed to Q Zhang.

At least 775 records · Page 43Linked to original sources

PubMed1995

The change of carnitine content in seminal plasma after reversible injection occlusion of vas deferens.

The change in carnitine content in seminal plasma after reversible injection occlusion of vas deferens (RIOVD) was observed. RIOVD is a safe, effective and simple method of male fertility control. Carnitine was determined by microenzymatic method. The incidence of sperm disappearance increased with the duration of RIOVD and reached 90% at the end of 12 months after operation. Before RIOVD, the mean value of carnitine in seminal plasma was 336.9 +/- 78.1 nmol/ml (X +/- SD, n = 58); after RIOVD, the mean value of seminal plasma carnitine was 112.7 +/- 50.7 nmol/ml (n = 172) in the group with sperm disappearance, and 172.5 +/- 71.7 nmol/ml (n = 51) in the group without sperm disappearance. There was a significant difference in carnitine content between pre-operation and postoperation (p < 0.01). After RIOVD, the carnitine concentration in seminal plasma of the group with sperm disappearance was lower than that of the group without sperm disappearance (p < 0.01). The results suggest that carnitine content in seminal plasma following RIOVD may be a reference index for judging the success or failure of the operation.

Carnitine↗

PubMed1995

Study on DNA-protein crosslinks induced by chromate and nickel compounds in vivo with 125I-postlabelling assay.

In an attempt to develop biomarkers of chromate and nickel exposure, we have used a rapid, simple and sensitive 125I-postlabelling assay to detect the formation of DNA-protein crosslinks (DPCs) in different tissues from male Sprague-Dawley rats exposed i.p. to potassium chromate (K2CrO4) and nickel chloride (NiCl2). The results demonstrated that 20 h after rats were injected i.p. with these agents, DPCs were observed in WBC, liver and kidney of rats treated with K2CrO4 in doses ranging from 10 to 40 mg/kg body wt. There was a dose-dependent relationship between chromate exposure and DPCs in WBC and liver, but no DPC increase was shown in lung. In the same way, DPCs were found in WBC and lung of rats treated with NiCl2 in doses ranging from 10 to 30 mg/kg in a dose-dependent manner. The formation of DPCs in different tissues was also observed following repeated exposure of rats to K2CrO4 and NiCl2 (10 mg/kg, i.p.) for 3 weeks. These results were similar with the single dose. It is indicated that chromate and nickel compounds possibly cause DNA or protein damage to form DPCs, suggesting DPCs might be useful as a biomarker for quantitative K2CrO4 and NiCl2 exposure and genotoxic lesions. In addition, WBC were shown to be more sensitive to chromate(VI) and nickel(II) induced DPCs than other targets. There were significant correlations between DPCs induced by K2CrO4 in WBC and liver, and by NiCl2 generated DPCs in WBC and lung, indicating that DPCs in WBC may be a good surrogate for some internal organs of humans exposed to chromate(VI) and nickel(II) compounds.

Animals↗

PubMed1995

Effect of administration of high dose intrathecal clonidine or morphine prior to sciatic nerve section on c-Fos expression in rat lumbar spinal cord.

The effects of moderate and high intrathecal doses of clonidine, an alpha 2 adrenoceptor agonist, or a high dose of morphine on sciatic nerve section-induced expression of c-Fos-like immunoreactivity was studied in laminae I and II of the dorsal horn and laminae VIII and IX of the ventral horn of rat lumbar spinal cord. c-Fos-like immunoreactivity was examined by immunohistochemistry in normal rats (group 1), rats implanted with an intrathecal catheter with its tip on the lumbar spinal cord (group 2), injected with 10 micrograms (group 3) or 50 micrograms (group 4) clonidine intrathecally 3 h before being killed. In other groups, saline, 10 or 50 micrograms clonidine or 30 micrograms morphine was injected 1 h before unilateral nerve section, and the expression of c-Fos-like immunoreactivity was examined 2 h after axotomy. Few labeled neurons were found in normal controls. The intrathecal catheter itself caused a significant increase in bilateral c-Fos-like immunoreactivity in spinal dorsal and ventral horn compared to normals. The level of c-Fos-like immunoreactivity after 10 or 50 micrograms intrathecal clonidine was similar as in the intrathecal catheter group. Sciatic nerve section caused a significant ipsilateral increase in c-Fos-like immunoreactivity in the dorsal horn compared to the intact side in rats injected with saline. Pretreatment with 10 or 10 micrograms clonidine did not reduce sciatic nerve section-induced expression of c-Fos-like immunoreactivity, but instead caused a significant bilateral increase in c-Fos-like immunoreactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Agonists↗

PubMed1995

Central and peripheral expression of galanin in response to inflammation.

Using in situ hybridization, immunohistochemistry and receptor binding methodology, the galanin messenger RNA levels, galanin binding and galanin-like immunoreactivity were examined in rats injected with carrageenan into the left hindpaw. Three days after injection, a distinct increase (63%) in galanin messenger RNA-positive neurons was observed in the medial laminae I and II of the ipsilateral dorsal horn (lumbar 4 and 5) as compared to the contralateral side. However, no alteration was found in galanin binding and galanin-like immunoreactivity in the dorsal horn. In dorsal root ganglia (lumbar 5), inflammation induced a significant decrease in galanin messenger RNA (39%) and galanin peptide (47%) on the ipsilateral side. Galanin binding was not detected in dorsal root ganglia, neither on the inflammatory nor on the control side. Increased levels of galanin-like immunoreactivity and galanin messenger RNA were seen in cells in the inflamed dermis and epidermis, especially in stratum granulosum. Most of the galanin-immunoreactive cells contained ED1-like immunoreactivity, a marker for macrophages. A strong galanin binding was seen in the inflamed dermis. Such binding sites may be targets for galanin released from local cells in inflamed dermis. Taken together, our results suggest that both neuronal and non-neuronal galanin or a galanin-like peptide is involved in the response to inflammation.

Animals↗

PubMed1995

Distribution of arachidonic, eicosapentaenoic, docosahexaenoic and related fatty acids in ovine endometrial phospholipids in late gestation and labor.

The quantitative distribution of phospholipid (PL) fatty acids from ovine endometrial tissues taken at 105 (n = 3) and 131 and 147 (n = 5) days of gestation age (dGA) and in spontaneous labor (SL, n = 3) is reported. Phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS), and lysophosphatidylcholine (LPC), were separated by thin layer chromatography (TLC) and analyzed for fatty acid composition by quantitative gas chromatography (GC). Saturates are found mainly in PS and PI and unsaturates predominantly in PC and PE. The major long-chain polyunsaturated fatty acids (LC-PUFA), arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), are found primarily in PC, PE, and PI. AA accumulates in PC, PI and PS (p < 0.05) from late gestation to term and significantly declines in PC and PS (p < 0.02) during labor, suggesting that ovine endometrium is a possible source of prostaglandin (PG) precursors. EPA decreases significantly from around 105 dGA to term and at labor in PC (p < 0.02) and in PI (p < 0.01), which may indicate the involvement of 3-series PGs in the regulation of uterine contraction. Unsaturation index (UI) and total PUFA increase from late gestation to term in PE (p < 0.05) and decrease during labor (p < 0.05). The ratios of n-6/n-3 PUFA increase in PI (p < 0.05) and in PC (p < 0.01) during labor mainly due to the decline of EPA in these PL.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Impedance analysis compared with Quickscan in the detection of graft-related stenoses.

OBJECTIVE: To compare two methods of detecting graft stenoses after infrainguinal bypass. DESIGN: Prospective study. SETTING: Vascular Laboratory, University Hospital. MATERIALS: 110 infrainguinal graft studies (60 vein, 50 PTFE) in 74 patients were performed prospectively to detect graft-related stenoses. CHIEF OUTCOME MEASURES: The diagnostic accuracy of computer assisted impedance analysis was assessed using Quickscan (QS) as the gold standard in the detection of graft-related stenoses. CHIEF RESULTS: QS showed occlusion in 4 grafts (two vein and two PTFE), no stenosis in 86 graft studies and stenoses in 20 studies. All 12 stenoses with a frequency ratio > or = 1.4, were confirmed with intraarterial digital subtraction angiography (IADSA). Eight stenoses with a frequency ratio of 1:3 continued graft surveillance. The median thigh impedance score of vein grafts with QS confirmed stenoses was 0.51 (0.36-0.70) compared with 0.44 (0.30-0.60) for non-stenosed vein grafts (p = 0.015, Mann-Whitney U test). The median thigh impedance score in PTFE graft with QS confirmed stenosis was 0.58 (0.53-0.76) compared with 0.42 (0.28-0.73 for non-stenosed grafts (p = 0.0001). An impedance score > 0.45 has been suggested for detection of "at risk" grafts. Using QS as the gold standard, impedance assessment gave 90% sensitivity, 63% specificity in the thigh; 80%, 52% in the calf and 90%, 46% taking the higher score on calf for thigh data. Taking a QS frequency ratio of 1:4 as indicating a significant stenosis (50% diameter reduction), 11% (12/106) of surveillance studies went on to intervention, that is 12/74 (16%) grafts. CONCLUSIONS: If the higher impedance score derived from either the calf or thigh was used to detect stenoses, 60% (64/106) of graft studies would have been referred for intervention. We believe this high level of intervention is unrealistic and cannot therefore recommend impedance analysis for graft surveillance.

Angiography, Digital Subtraction↗

PubMed1995

Physiological and perceived exertion responses to six modes of submaximal exercise.

In order to compare the cardiovascular and perceived exertion responses to 6 modes of exercise, 10 male recreational exercisers were habituated to treadmill jogging, stationary skiing, shuffle skiing, stepping, stationary cycling, and stationary rowing. After following a specific dietary preparation, each participant performed a 20-min exercise bout at a constant 14-rating of perceived exertion (RPE) followed by a second exercise bout at 60% of mode-specific peak oxygen consumption (VO2peak). On the 14-RPE trial, oxygen consumption (VO2) and oxygen pulse were significantly higher during jogging than during other exercise modes, and oxygen pulse was higher during skiing than during shuffle skiing. On the 60% VO2peak bout, oxygen pulse was significantly higher during jogging than during shuffle skiing, cycling and rowing. Ratings of perceived exertion were significantly higher during cycling than during jogging. These results indicated that a variety of exercise modes can be used to develop fitness, but jogging may induce a slightly more favorable VO2-to-RPE relationship.

Adult↗

PubMed1995

Common genetic variants of lipoprotein lipase that relate to lipid transport in patients with premature coronary artery disease.

Two common coding sequence mutations of lipoprotein lipase (serine447-ter, producing a carboxy terminal truncation; and asp9-asn variants) were studied in 329 Caucasian subjects, of whom 243 had angiographic features of premature atheroscelerosis (220 with coronary artery disease; 23 with coronary and peripheral artery disease). As expected, the mean levels of cholesterol, triglycerides, LDL-cholesterol, ApoB and Lp(a) were significantly higher in the arterial disease group than in the controls. HDL levels were lower in the patient group. With regard to the common mutations, plasma triglycerides and VLDL-triglycerides were lower in subjects possessing the Serine447-Ter mutation (p = 0.06 and < 0.05, respectively). When the lipid distributions were analysed by tertiles, the Ser447-Ter mutation was significantly less frequent in the highest tertiles for triglycerides (p < 0.02), and VLDL (p < 0.04). The Asp9-Asn substitution was significantly more frequent in the lowest tertiles for ApoAI (p = 0.05). Case-control analyses of genotypic distributions between the two groups with or without arterial disease did not show any significant differences. The possible functional effects of these common mutants of lipoprotein lipase are discussed.

Asparagine↗

PubMed1995

Influence of hemodialysis membranes on gene expression and plasma levels of interleukin-1 beta.

Plasma levels of interleukin-1 beta (IL-1 beta) were measured in 10 normal subjects, in 11 nondialyzed end-stage renal failure (ESRD) patients, and in 22 hemodialysis (HD) patients. Of the HD patients, 7 were dialyzed with Cuprophan (CU), 7 with polymethylmethacrylate (PMMA), and 8 with polysulphone (PS) dialyzers. In normal controls, nondialyzed ESRD patients, and HD equipped with CU, PAMM, and PS dialyzers, plasma levels of IL-1 beta were 10.73 +/- 5.24 pg/ml, 9.97 +/- 3.61 pg/ml, 13.17 +/- 4.04 pg/ml, 15.16 +/- 6.16 pg/ml, and 13.96 +/- 5.47 pg/ml, respectively. There were no statistically significant differences among the groups (p > or = 0.05). In contrast, the gene expression of IL-1 beta for peripheral blood mononuclear cells (PBMC) by in situ hybridization showed differences among the groups. The gene for IL-1 beta for PBMC appears in HD equipped with different membranes, but not in cases of nondialyzed uremic patients and normal subjects. With computer imaging analysis, we carried out quantitative analysis of cells in in situ hybridization with an area of positive spots to an area of total cells. In HD with CU, PMMA, and PS, the results were 10.64 +/- 1.07, 3.34 +/- 0.74, and 3.27 +/- 0.64%, respectively. The levels of IL-1 beta gene expression in CU were higher than that in PMMA or PS. There were statistically significant differences (p < or = 0.001) between CU and PMMA or PS and no significant difference between the PMMA and PS (p > or = 0.05). We suggest measuring the gene expression of cytokines for PBMC and which may be better than measuring cytokine levels only for investigating the blood compatibility of dialyzers, which may help in understanding chronic complications of the dialysis procedure.

Adult↗

PubMed1995

Genetic Diversity of Xanthomonas oryzae pv. oryzae in Asia.

Restriction fragment length polymorphism and virulence analyses were used to evaluate the population structure of Xanthomonas oryzae pv. oryzae, the rice bacterial blight pathogen, from several rice-growing countries in Asia. Two DNA sequences from X. oryzae pv. oryzae, IS1112, an insertion sequence, and avrXa10, a member of a family of avirulence genes, were used as probes to analyze the genomes of 308 strains of X. oryzae pv. oryzae collected from China, India, Indonesia, Korea, Malaysia, Nepal, and the Philippines. On the basis of the consensus of three clustering statistics, the collection formed five clusters. Genetic distances within the five clusters ranged from 0.16 to 0.51, and distances between clusters ranged from 0.48 to 0.64. Three of the five clusters consisted of strains from a single country. Strains within two clusters, however, were found in more than one country, suggesting patterns of movement of the pathogen. The pathotype of X. oryzae pv. oryzae was determined for 226 strains by inoculating five rice differential cultivars. More than one pathotype was associated with each cluster; however, some pathotypes were associated with only one cluster. Most strains from South Asia (Nepal and India) were virulent to cultivars containing the bacterial blight resistance gene xa-5, while most strains from other countries were avirulent to xa-5. The regional differentiation of clusters of X. oryzae pv. oryzae in Asia and the association of some pathotypes of X. oryzae pv. oryzae with single clusters suggested that strategies that target regional resistance breeding and gene deployment are feasible.

Journal Article↗

PubMed1995

Identification and characterization of a Mycoplasma hyopneumoniae adhesin.

An adhesin of Mycoplasma hyopneumoniae was identified and characterized in this study. A monoclonal antibody (MAb), F2G5, and its F(ab')2 fragments inhibited the adherence of M. hyopneumoniae to porcine tracheal cilia, the natural targets to which the mycoplasma binds during infection. MAb F2G5 detected multiple bands, but predominantly recognized a 97-kDa (P97) protein of M. hyopneumoniae on immunoblots. Affinity chromatography, conducted with immobilized MAb F2G5, mainly purified P97. The purified proteins were able to bind to cilia and blocked the adherence of intact M. hyopneumoniae cells to cilia. Immunolabeling of mycoplasmas with MAb F2G5 under electron microscopy demonstrated that the proteins recognized by MAb F2G5 were located at the surface of the mycoplasma, predominantly on a surface fuzzy layer. These results indicate that P97 functions as an adhesin of M. hyopneumoniae. The N-terminal amino acid sequence of P97 did not have significant homology with any known bacterial or mycoplasmal adhesins, suggesting that P97 is a novel protein. The predominant proteins detected by MAb F2G5 in different strains varied in size, indicating that the antigen bearing the epitope for MAb F2G5 undergo intraspecies size variation. Antigenic variation of adhesins may be a pathogenic mechanism utilized by M. hyopneumoniae to evade the porcine immune system.

Adhesins, Bacterial↗

PubMed1995

Ischemia-reperfusion increases gastric motility and endothelin-1-induced vasoconstriction.

The purpose of our study was to 1) examine the effect of ischemia-reperfusion on gastric vascular resistance and motility, 2) determine whether endothelin-1 (ET-1)-induced vasoconstriction is enhanced after ischemia-reperfusion, and 3) assess the effect of superoxide dismutase (SOD) on these ischemia-reperfusion-induced alterations. These experiments used a mechanically perfused ex vivo gastric segment of chloralose-anesthetized dogs. We first evaluated the effect of varying the duration of total ischemia on reperfusion-induced changes in gastric vascular resistance and motility. In other experiments, responses to ET-1 (10(-10) M) were compared before and after 30-min ischemia and 30-min reperfusion, with saline or SOD (10 U/ml) infused intra-arterially to the stomach during reperfusion. Our results show that 1) after ischemia, vasodilation is seen initially on reperfusion followed by a slowly developing, progressive increase in vascular resistance, 2) the force of gastric contractions was reduced during ischemia but elevated immediately on reperfusion, 3) vasoconstrictor responses to ET-1 are enhanced after ischemia-reperfusion, and 4) SOD reduced the enhanced response to ET-1 and force of contractions. Our findings support the hypothesis that reactive oxygen metabolites contribute to augmented vascular reactivity and hypercontractility after ischemia-reperfusion.

Animals↗

PubMed1995

Relationship between frequency and amplitude dependence in the lung: a nonlinear block-structured modeling approach.

During lung constriction, there is an increase in both the frequency and tidal volume (VT) dependences of lung tissue resistance (Rti) and elastance (Eti). This suggests that 1) significant alterations take place in the mechanisms contributing to both the linear and nonlinear characteristics of lung tissues; and 2) the frequency and VT dependences of Rti and Eti are coupled. We examined these issues for the case of sine wave and special pseudorandom inputs by utilizing the theory of nonlinear block-structured systems. Two basic model structures were considered: the Hammerstein and the Wiener structures. The Hammerstein structure is a cascade connection of a nonlinear zero-memory (N) system and a linear dynamic process (L). This structure predicts that frequency and VT dependences of Rti and Eti are decoupled. The Wiener structure is an inverse cascade of these two blocks (i.e., L-N) in which the frequency and VT dependences of Rti and Eti are coupled. These two structures were combined with a nonlinear airway compartment and fitted to measured airway opening and alveolar capsule pressure-flow time domain data in dogs before and after histamine-induced constriction. The best lung model was a linear airway compartment combined with a Wiener structure consisting of a constant-phase linear tissue impedance in cascade with a polynomial nonlinearity, suggesting that frequency and VT dependences of Rti and Eti are indeed coupled during control and constricted conditions. Moreover, histamine caused much larger changes in the linear tissue parameters than in the nonlinear coefficients.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pressure↗

PubMed1995

ApoA-IHelsinki (Lys107-->0) associated with reduced HDL cholesterol and LpA-I:A-II deficiency.

A Finnish kindred with premature coronary heart disease and decreased HDL cholesterol levels was identified as having an apoA-I variant, apoA-I (Lys107-->0), caused by a 3-bp deletion of nucleotides 1396 through 1398 in exon 4 of the apoA-I gene. These subjects (n = 10) were heterozygous for this mutation. The mean serum HDL cholesterol concentration (26.7 +/- 9.7 mg/dL) of affected family members was 36%, lower than that of unaffected family members (P < .05). Mean serum apoA-I and apoA-II concentrations in heterozygotes were reduced by 18% and 22%, respectively, compared with normal family members (P < .05). In heterozygotes the mean concentration of lipoprotein containing both apoA-I and apoA-II (LpA-I:A-II) was 31% lower than in those with normal apoA-I (P < .001), while the mean level of lipoproteins containing apoA-I without apoA-II was similar in the two groups. HDL density-gradient ultracentrifugation showed a lack of HDL2 and small dense HDL3 in heterozygotes compared with unaffected family members. The HDL particle size distribution, as analyzed by nondenaturing gradient gel electrophoresis of heterozygotes, revealed one major peak at 8.0 to 9.7 nm, a minor peak at 7.8 to 8.5 nm, and an absence of HDL2b and HDL2a peaks. These latter peaks were observed in unaffected family members. Serum levels of LDL cholesterol, triglycerides, VLDL, IDL, and LDL subclasses were similar in the two groups. However, in heterozygotes the cholesterol-to-triglyceride ratios in VLDL2, LDL1, LDL3, HDL2b, HDL2a, and HDL3a were 8% to 54% lower than in unaffected family members (P < .05). Cholesteryl ester transfer protein activity in heterozygotes was reduced by 25% compared with unaffected family members (P < .05), while the plasma lecithin:cholesterol acyltransferase (LCAT) activity did not differ between heterozygotes and unaffected family members. The ability of isolated variant apoA-I to serve as a cofactor for LCAT in vitro did not differ from that of normal apoA-I. Our data are consistent with the concept that a low HDL cholesterol level in subjects heterozygous for the apoA-IHelsinki mutation (Lys107-->0) having normal LCAT activity is a consequence of decreased concentration of LpA-I:A-II particles and of a smaller size and reduced cholesterol content of HDL particles.

Apolipoprotein A-I↗

PubMed1995

Temperature-dependent responses of rats to ergovaline derived from endophyte-infected tall fescue.

Ergovaline, found in Acremonium coenophialum-infected tall fescue, is considered to be responsible for many symptoms associated with fescue toxicosis. Rats were tested to determine time-related thermoregulatory responses to acute treatment with ergovaline during specific thermal challenges. Isolated ergovaline was administered to rats (15 micrograms/kg body mass, i.p.) at controlled ambient temperatures (Ta) of 7 to 9 degrees C (cold) and 31 to 33 degrees C (hot). Treatment at cold Ta resulted in a decrease in rectal temperature (Tre) from 38.0 to 37.0 degrees C at 50 min after injection (P < .05) without complete return to preinjection value at 100 min. Tail temperature (Ttail) exhibited a concomitant 1C degree decrease (P < .05) after ergovaline injection at cold Ta. Also, metabolic heat production decreased from 15.7 to 11.7 W/kg at 20 min after injection of ergovaline (P < .05), with return to normal value at 40 min after injection. Injection of ergovaline at hot Ta increased Tre from 39.0 to 40.6 degrees C at 80 min after injection (P < .05), with no return to preinjection value at 100 min. This was attributed to a reduction in heat transfer across the tail as indicated by the decrease in Ttail from 37.1 to 36.4 degrees C at 40 min after injection (P < .05) and an initial increase in metabolic heat production from 8.4 to 9.4 W/kg at 3 min after injection (P < .05). Ambient temperature was found to be a major determinant of ergovaline response, which included alterations in both thermogenic and thermolytic mechanisms that control thermal balance.

Acremonium↗

PubMed1995

Regulation of bone sialoprotein gene transcription by steroid hormones.

During the initial formation of bone, dentine and cementum in tooth morphogenesis, fully differentiated osteoblasts, odontoblasts and cementoblasts express bone sialoprotein (BSP), a mineralized tissue-specific acidic glycoprotein that has been implicated in the nucleation of hydroxyapatite crystal growth. The expression of BSP is regulated by steroid hormones that modulate mineralized tissue formation. Thus, the transcription of the BSP gene is induced by glucocorticoids in association with osteoblast differentiation and glucocorticoids also stimulate the expression of BSP in differentiated osteoblasts. In contrast, however, vitamin D3 suppresses bone formation and abrogates the expression of BSP. Our studies, using the osteoblastic cell lines ROS 17/2.8 and UMR 106-06, have revealed that the glucocorticoid (10(-8) M dexamethasone; dex) effect on BSP mRNA involves both direct and indirect pathways. To determine the molecular basis of the direct pathway on transcriptional regulation of the BSP we have isolated and characterized the promoter regions of both the human and rat BSP genes. The promoters are characterized by a highly conserved region (BSP box) encompassing the immediate promoter region, which includes a unique inverted TATA box overlapped by a putative (DR3) vitamin D3 response element (VDRE). Possible glucocorticoid response elements are present approximately 1 kb and approximately 1.4 kb further upstream. Transient transfection analysis of chimeric constructs linked to a luciferase reporter gene have shown Dex-stimulated expression in constructs that include one or both GREs, whereas vit D3 suppresses expression in a short construct that includes the VDRE.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Localization of multiple functional domains on human PECAM-1 (CD31) by monoclonal antibody epitope mapping.

PECAM-1, a cell adhesion molecule of the immunoglobulin gene (Ig) superfamily, has been implicated in white cell transmigration, integrin activation on lymphocytes, and cell-cell adhesion. The purpose of this investigation was to identify specific regions of the PECAM-1 extracellular domain mediating these functions by identifying the location of epitopes of bioactive anti-PECAM-1 monoclonal antibodies. The binding regions of mAbs important in PECAM-1-mediated leukocyte transmigration (Hec 7.2 and 3D2) were mapped to N-terminal Ig-like domains. The epitopes of monoclonal antibodies that activated integrin function on lymphocytes were dispersed over the entire extracellular region, but those that had the strongest activating effect were preferentially localized to the N-terminus of the molecule. The binding regions of mAbs that blocked PECAM-1-mediated heterophilic L-cell aggregation were located either in Ig-like domain 2 (NIH31.4) or Ig-like domain 6 (4G6 and 1.2). Site-directed mutagenesis further pinpointed the epitope of the 4G6 mAb to a hexapeptide, CAVNEG, within Ig-like domain 6. These results demonstrate that PECAM-1 contains multiple functional domains. Regions within N-terminal Ig-like domains appear to be required for transmigration. In contrast, two distinct regions were implicated in L-cell mediated heterophilic aggregation.

Amino Acid Sequence↗

PubMed1995

Cytosinine: pyridoxal phosphate tautomerase, a new enzyme in the blasticidin S biosynthetic pathway.

Cytosinine--the nucleoside portion of blasticidin S--and pyridoxal phosphate were incubated with cell-free extracts of Streptomyces griseochromogenes prepared in D2O. 2H NMR analysis of recovered cytosinine showed it to contain deuterium enrichments at H-4' and H-2'. No exchange was observed with either boiled extract or from cytosinine and pyridoxal phosphate alone. These results reveal the presence of a tautomerase activity that contributes to the net transamination at C-4' in the conversion of cytosylglucuronic acid to blasticidin S, and its discovery supports the role of cytosinine as a biosynthetic intermediate.

Antifungal Agents↗